B cell differentiation factor production in systemic lupus erythematosus.

Spontaneous and mitogen stimulated B cell differentiation factor (BCDF) production by peripheral blood lymphocytes (PBL) from patients with systemic lupus erythematosus (SLE) was compared with that of normal control subjects. BCDF production was measured by a cellular interleukin assay in which a BCDF responsive cell line was cocultured with increasing numbers of PBL from the donor populations. It was found that no significant differences occurred in BCDF production by SLE and normal PBL under the conditions used. Indeed there was a trend toward decreased BCDF release from SLE PBL. This would support the hypothesis that human SLE is the result of enhanced B cell responsiveness to helper cell factors rather than due to increased release of such factors.